A current i is carried by a long, straight wire. The magnetizing field intensity H is determined at a point P close to the wire. A long, cylindrical iron rod is then brought near the wire such that point P is located at the centre of the rod. The value of H at point P will

Step-by-step solution

The magnetizing field intensity H at a distance r from a long straight wire carrying current i is given by Ampere's law: H d l = i_ free H = i 2 r The value of the magnetizing field H depends only on the free current i and the distance r . It is independent of the magnetic medium present. When a cylindrical iron rod is placed such that point P is at its centre, the magnetic induction B at P increases many times because B = _r ₀ H and iron has a high relative permeability ( _r 1 ). However, since the free current i